How the Pace Calculator Works
Training Through Pace and Heart Rate
Pace measures your speed of movement, while heart rate tracks how many times your heart contracts each minute. Because these metrics share a positive correlation—meaning a higher pace naturally elevates your heart rate—combining them in your routine helps improve performance, track long-term fitness progress, and prevent overtraining.
Chart: race times at a 5:00 per kilometer pace
Keep the same pace of 5:00 per kilometer (8:03 per mile), and the finish time grows with the distance:
1K █ 5:00 5K █████ 25:00 10K █████████ 50:00 Half-marathon ████████████████████ 1:45:29 Marathon ████████████████████████████████████████ 3:30:59
Chart: pace and speed
A faster pace is a shorter time per kilometer, which is a higher speed. Speed = 3600 divided by the seconds per kilometer:
4:00 per km ████████████████████████████████████████ 15.00 km/h 5:00 per km ████████████████████████████████ 12.00 km/h 6:00 per km ███████████████████████████ 10.00 km/h 7:00 per km ███████████████████████ 8.57 km/h 8:00 per km ████████████████████ 7.50 km/h
Tracking and Estimating Heart Rate Zones
You can measure your heart rate with dedicated monitors or by checking your pulse manually at the wrist or neck. Two vital baseline measurements include:
Resting Heart Rate (RHR): Typically ranges between 60 to 100 bpm (though some experts suggest 50 to 90 bpm). Efficient heart function often correlates with a lower RHR, but rates consistently outside the 50–90 bpm window can signal underlying health concerns.
Maximum Heart Rate (MHR): While clinical stress tests offer the most precise measurement, they are time-consuming. Consequently, many athletes rely on age-based formulas. The most common—though imperfect and lacking standard deviation references—is MHR = 220 – age. Despite its limitations, it serves as a useful benchmark for setting training zones, such as the 60–70% MHR range, which is ideal for burning fat.
Aerobic vs. Anaerobic Exercise
Endurance training heavily relies on understanding the balance between aerobic and anaerobic states, which differ primarily by duration, intensity, and how muscles generate energy:
Aerobic Exercise (~70–80% MHR): Involves light, sustained activity over long periods where oxygen supply meets energy demand. To get the best results, fitness professionals generally recommend maintaining 55–85% of MHR for 20 to 30 minutes.
Anaerobic Exercise (~80–90% MHR): Involves short, intense bursts of effort. Because the cardiovascular system cannot supply oxygen fast enough, muscles break down sugar directly, producing excess lactate. This buildup causes the familiar "burn" in muscles and eventually forces you to stop if not given time to clear.
Marathon Training and Thresholds
For long-distance events like marathons, mastering your aerobic threshold pace is crucial. This is a sustainable, low-intensity pace that balances fat and carbohydrate usage for hours. Conversely, the anaerobic threshold marks the point where lactic acid builds up faster than the body can clear it.
While lab testing provides the most accurate thresholds, you can estimate your Lactate Threshold Heart Rate (LTHR) through a field test:
Run a 30-minute time trial alone at maximum effort.
Calculate your average heart rate over just the last 20 minutes of the run to estimate your anaerobic threshold. (Note: Group time trials require a full 60-minute duration).
Subtract 30 beats per minute from your estimated anaerobic threshold to find your approximate aerobic threshold heart rate.
Ultimately, threshold training trains your body to delay lactate buildup, postpone fatigue, and help you run faster and farther.
Are you planning to incorporate these heart rate zones or threshold tests into a specific running or cardio schedule?